Currently, a paper, a white plastic film, etc. are generally used as a substrate of a label, a leaflet, a card, a calendar, and the like, and polyvinylchloride, polyolefin, polystyrene, and the like are used as plastics.
Generally, a polyolefin film containing inorganic fine particle has been frequently used as a substrate for paper substitute, however the polyolefin film has poor mechanical strength, poor heat resistance, poor weather resistance and poor dimensional stability, so its uses are limited. These days, a polyester film is increasingly used for several use of a paper substitute.
The white film has been used for label, graphic, and the like that considers a concealment or printing as important, however recently, their uses are expanding to all sorts of packaging food (yogurt cap, etc.), industrial insulation, solar cell, backsheet. For this reason, there is the problem that the oligomer in the film is extracted by the migration phenomenon when increasing the temperature of film.